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    Re: Gnomonic Charts - Usable Zones
    From: Antoine Couëtte
    Date: 2018 Jan 19, 08:24 -0800

    Dear Bob,

    In the early 80's, HP published a remarkable HP41 NAVIGATION PAC, in which the GCPLOT Program solves your both requests. Probably TI did the same by that same time.

    I am sure such an equivalent Program is available to-day, e.g. :

    • Either in the Navigation Corpus of André Ruiz : https://sites.google.com/site/navigationalalgorithms/ , or:
    • In the Spread Sheets Corpus of Peter Hakel : http://www.navigation-spreadsheets.com/, or:
    • Possibly in both. André and Peter are regular and highly regarded Contributors to NavList.

    As a last resort, and if you have at hand a software enabling to immediately switch reference coordinates, and among different approaches I would suggest that from the well known LAT/LONG Coordinates Reference, you switch into a "New Coordinates Reference" such as:

    • The "New Equator" includes either:
      • your departure and arrival points, or:
      • your departure point and your departure heading.And
    • The "New Equator Longitudes" departure point is your own position.

    Hence your problem is immediately solved through just choosing your distances alongside the "New Equator". To plot your results on Earth, simply perform the coordinates Transformation backwards into Standard LAT/LONG Coordinates.

    If you can easily visualize changes of Reference Coordinates in 3D, this is a quite straightforward approach.

    Certainly, both Peter and André among many others can give you more immediately usable answers.

    If you cannot get what you exactly need, do not hesitate to revert to me onto my private e-mail.

    Best Regards,

    Antoine Couëtte

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